1. Field of the Invention
The present invention relates to a porous region removing method and a semiconductor substrate manufacturing method and, more particularly, to a method of removing a porous region from a substrate having the porous region, a semiconductor substrate manufacturing method using this method, and an apparatus for removing a porous region.
2. Description of the Related Art
There is a method of sequentially forming a porous Si layer and a single-crystal Si layer on a first substrate, bonding the first substrate to a separately prepared second substrate, and separating the bonded substrate stack into two substrates at the porous Si layer to transfer the single-crystal Si layer formed on the first substrate side to the second substrate side, thereby manufacturing an SOI substrate.
In this method, after the bonded substrate stack is separated into two substrates, the porous Si layer remaining on the surface on the second substrate side is removed. In removing the porous Si layer, the planarity of the surface of the underlying second substrate and, more particularly, film thickness uniformity of the single-crystal Si layer as the surface layer of the second substrate is preferably not hindered.